Roy,
> Hi all
>
> There was some discussion on #opensolaris recently about L2ARC being
> dedicated to a pool, or shared. I figured since it's associated with a pool,
> it must be local, but I really don't know.
An L2ARC is made up of one or more "Cache Devices" associated with a single ZFS
storage pool. Caching device(s) can be associated with a ZFS storage pool at
either 'zpool create ...' time or later with 'zpool add ...'
# zpool create pool_0 mirror c8t0d0 c9t0d0 mirror c8t0d1 c9t0d1 cache
c7t0d0 c7t1d0
or
# zpool add pool_0 cache c7t0d0 c7t1d0
If one finds that a caching device is being underutilized within a given ZFS
storage pool it can be removed, and reprovisioned into another pool.
# zpool remove pool_0 cache c7t1d0
# zpool add pool_1 cache c7t1d0
In regards to sharing of cache devices between multiple ZFS storage pools, ZFS
supports taking a device, using 'format ....' to partition the device into
multiple slices, and then to add selected slices into different ZFS storage
pools. For data devices in a ZFS storage pool this disables the
Write-Cache-Enable setting, potentially impacting performance, but this does
not appear to impact SSD devices, when used as either log or cache devices.
# zpool remove pool_0 cache c7t1d0
# format c7t1d0
format > ....
.
.
# zpool add pool_0 cache c7t1d0s0
# zpool add pool_1 cache c7t1d0s1 (or other slices based on the manual
formatting done above)
NOTE: The omission of either slice designator ('s0' or 's1' above), will cause
ZFS to (re)format the whole device, undoing any manual partitioning done with
format.
Jim
>
> So - is it local to a pool, or global?
> If it's global, will I need to do something for mypool's l2arc to be used for
> other pools?
>
> Vennlige hilsener / Best regards
>
> roy
> --
> Roy Sigurd Karlsbakk
> (+47) 97542685
> r...@karlsbakk.net
> http://blogg.karlsbakk.net/
> --
> I all pedagogikk er det essensielt at pensum presenteres intelligibelt. Det
> er et elementært imperativ for alle pedagoger å unngå eksessiv anvendelse av
> idiomer med fremmed opprinnelse. I de fleste tilfeller eksisterer adekvate og
> relevante synonymer på norsk.
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